import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

public class Solution1 {
    public int[] twoSum(int[] nums, int target) {
        Map<Integer,Integer> map=new HashMap<>();
        for (int i=0;i<nums.length;i++){
            if (map.containsKey(target-nums[i])){
                return new int[]{map.get(target-nums[i]),i};
            }
            map.put(nums[i],i);
        }
        return null;
    }

    public static void main(String[] args) {
        System.out.println(Arrays.toString(new Solution1().twoSum(new int[]{2, 7, 11, 15}, 9)));
    }
}
